1. Field of the Invention
The present invention relates to a photovoltaic module, and more particularly, to a photovoltaic module in which a plurality of solar cells is sealed with a sealant between a light-transmitting substrate and a rear surface member.
2. Description of Related Art
From the viewpoint of global environment, attention is being given to solar cells that can convert light from the sun, which is a clean inexhaustible energy source, directly into electricity.
Because a single solar cell outputs as small as a few watts, generally a plurality of solar cells is electrically connected in series to enhance the output to a few hundreds watts and used as a photovoltaic module to power houses and buildings.
The conventional photovoltaic module will be descried according to FIGS. 20 and 21. FIG. 20 is a cross-sectional view partially illustrating the structure of the conventional photovoltaic module. FIG. 21 is a plan view illustrating the conventional photovoltaic module.
As illustrated in FIG. 20, a plurality of solar cells 800 is electrically interconnected through tab connectors 802 composed of an electrically-conductive material such as copper foil. The solar cells 800 are sealed with a light-transmitting sealant 840 such as EVA (Ethylene Vinyl Acetate) having excellent weather resistance and moisture resistance between a light-transmitting front surface member 830 such as glass and light-transmitting plastic and a rear surface member 820 composed of a water weather-resisting film.
As illustrated in FIG. 21, the plurality of solar cells 800 is connected in series through the tab connectors 802 so as to form a unit (strings) 810. Connectors, so-called interconnectors 811 are used for connecting between these units 810, 810. These interconnectors 811 are arranged surrounding the solar cells 800. Additionally, lead-out wires are connected with the interconnectors 811 inside a terminal box (not shown) so as to draw an output from these solar cells 800 to the outside.
As mentioned above, the photovoltaic submodule is formed. Then, a photovoltaic module will be structured by arranging a metallic outer frame 850 surrounding the photovoltaic submodule.
In the aforementioned photovoltaic submodule, the front surface member 830, a front surface side sealing material sheet, the tab connectors 802, the plurality of solar cells 800 connected through, for example, the interconnectors 811, a rear surface side sealing material sheet, and the rear surface member 820 are laminated in this order, set in a equipment, a so-called laminator, and then pressed to be integrated, while being heated under reduced pressure.
It is preferred that the aforementioned interconnectors 811 have large cross-sectional area in order to reduce resistance loss. These interconnectors 811 are arranged at the periphery of the units 810. Therefore, when an area occupied by the interconnectors 811 is increased, an area of the photovoltaic submodule is increased by that much. This reduces a share of a power generating region of a module area (light-receiving area). As a result, module efficiency is reduced.
From the viewpoint of module efficiency, the interconnectors 811 have conventionally a reduced line width and an increased thickness in order to reduce the resistance loss.
A fully solder-coated copper foil having a thickness of approximately 300 μm and a width of approximately 2 mm to 7 mm is cut into a specified length. The cut one is used for the aforementioned conventional interconnectors 811.
A proposed photovoltaic module includes unnoticeable interconnectors arranged surrounding solar cells. It improves the whole appearance design of building and the like, in which the photovoltaic module is provided. (e.g. Japanese unexamined patent publication No. 2005-79170) The photovoltaic module described in the Japanese unexamined patent publication is structured to arrange a colored light-receiving-side charging material at the periphery end of the photovoltaic module, thereby hiding the interconnectors and the like.